Objective: To study the spectral characteristics of the phototherapy systems and to identify variations in spectral properties
with changes in height, voltage, tilt and temperature output.
Setting:Research laboratory at a tertiary care hospital.
Methods: The spectral characteristics were measured from two compact fluorescent lamp (CFL) and eight light emitting diode
(LED) phototherapy devices in a dark room with an irradiance of <0.1μW/cm2/nm. The variations in the spectral characteristics
with changes in height, tilt and voltage were measured. Heat output was documented.
Results: The peak spectral wavelength of all the devices tested had a peak centering around 450±10 nm, in billirubin absorption
spectrum. LEDs achieved a higher maximum irradiance compared to CFL units across all the heights tested. CFL and Array LEDs
showed a better mean irradiance compared to Spot/Multispot LEDs. CFL and Array LEDs demonstrated the best footprint whereas
the Spot and Multispot LED units had a narrow footprint (approximately half or less of CFL or Array LEDs).Tilt angles influenced the
mean irradiance. Most of the units showed a decrease in mean irradiance with tilting except for one Array LED namely Brilliance
Classic. CFLs showed an inconsistent mean irradiance when tested at different voltage inputs LEDs had a consistent irradiance in
spite of voltage fluctuations. LEDs had minimal irradiance decay of irradiance compared to CFLs. Both CFL and LED units showed
increasing temperature output over time, which is more pronounced in CFL units.
Conclusion: The phototherapy units differ in spectral properties which influence their therapeutic efficacy. Spectral parameters
and its variations with tilt height and voltage changes must be considered when phototherapy device are used. The Array LEDs and
CFL devices seem to score over other devices in most of the parameters tested.